Manufacture of improved lubricating compositions



Patented Mar. 1, 1938 MANUFACTURE OF IMPROVED LUBRIOAT- ING COMPOSITIONS Troy Lee Cantrell and James Otho Iurncr, Lansdowne, Pa., asslgnors to Gulf Oil Corporation, Pittsburgh, Pa, a corporation of Pennsylvania No Drawing. Application September 2, 1936, Serial No. 99,158

10Claims.

This invention relates to improved lubricants and processes of making the same; and it comprises lubricating compositions and lubricants containing small amounts of improvement agents which mitigate or retard the normal destructive action of lubricating oil deterioration products on certain bearing surfaces, the improvement in this respect being noteworthy with even such bearing materials as alloys of cadmium with copper and silver, of cadmium with copper and nickel, of lead with copper and nickel, etc., even under relatively high temperatures, speeds and pressures, this improvement of the min eral oil being eflected and its performance improved by the presence therein of a small amount of a thioether of alpha-anthraquinone; and it also comprises methods of making an improved oil wherein such a thioether, which is advantageously an alpha-anthraquinone alkyl thioether, is incorporated in the oil prior to application of the lubricant to a bearing; all as more fully hereinafter set forth and as claimed.

Recent developments in the design of mechanical equipment for generating and transmitting power, and particularly in the automotive field, have necessitated new bearing metals with special properties. Among these new bearing materials are binary and ternary alloys of the metals mentioned above. Cadmium-silver-copper, cadmium-nickel-copper, copper-lead-nickel, etc., alloys are in use. One ternary alloy currently used in automobile engines is an alloy of cadmium with minor amounts of both silver and copper. Under the conditions imposed by modern engineering design these new alloys are frequently subjected to more severe operating conditions than were usual in the older art: to higher bearing loads, higher rubbing speeds and higher temperatures of operation. It is found that in actual use under these conditions there often develops serious destructive action on the bearing surface by mineral lubrieating oils, even by those standard commercial oils giving particularly good results with the older bearing metals under the earlier operating conditions. The destruction of the bearing metal probably results from the action of deterioration products developed in the oil. An object achieved in the present invention is the production of lubricating oils improved for these newer conditions of use and which are characterized by reduction or elimination of destructive action on the newer bearing metals by deterioration products in the oil.

We have discovered that the thioethers of alpha-anthraquinone, incorporated with lubricants, are capable of achieving the objects of the present invention, the alkyl thioethers, such as those containing the various amyl groups, being particularly effective. By adding small amounts of such thioethers to the mineral oil or lubricant, we obtained improved lubricating compositions which satisfactorily lubricate the said alloy bearings. Incorporated in the mineral oil, these thioethers retard destruction of the bearing metal. Also, the film strength of the lubricant is increased, the thioethers imparting extreme pressure characteristics to the oil. The character and amount of added improvement agents, here employed, are such that the normal physical properties of the oil, such as viscosity, gravity, etc., are not substantiallyaltered. Thus, by the present invention, certain properties of the lubricant are improved without sacrificing the other and desirable properties of the lubricating oil.

In this way, we obtain improved mineral oils and lubricants suitable for lubricating such bearings under a wide range of service conditions. The new compounded lubricant satisfactorily lubricates the new alloy bearings even under high unit pressure and high temperature. When prepared from suitable motor oils, the present improved compositions are excellent lubricants for the modern automobile engine. They satisfactorily lubricate the bearings without any destruction of the special bearing alloys now used, even in the presence of a free circulation of air.

Ordinarily between 0.05 and 0.5 per cent of the thioether are sumcient to produce a satisfactory lubricant. However, in some cases larger amounts of the thioethers may be employed, for instance, with those oils of more pronounced destruction tendency. As much as l per cent of thioether may sometimes be added with advantage. The particular proportions depend upon the particular thioether and lubricating base employed and the particular type of lubricant desired.

When larger amounts are employed, extreme pressure characteristics are also imparted to the mineral oil lubricant. In many cases, the load .carrying capacity of the lubricant may be increased by 50 to per cent. Thusthe addition of the thioether gives the compounded lubricant several advantageous properties. As stated ante, even a fraction of a per cent produces the described results.

The thioethers here employed to improve the mineral oil and lubricating compositions may be represented by the following formula wherein R represents a hydrocarbon radical, advantageously an alkyl group. As a class, these thioethers are soluble and miscible with mineral oils in limited proportions. However, we have found that they are suiiiciently soluble and miscible to permit incorporation with the mineral oil of an amount of thioether suflicient to obtain the described improvement.

These thioethers may be prepared by reacting the sodium salt of anthraquinone alpha sulphonic acid with a sodium alkyl sulphide in aqueous solution, the following equation illustrating the typical reaction:

OsNa

By employing other sodium hydrocarbon sulfides, other thioethers may be obtained in a similar manner. Thus the R in the structural formula given ante, may represent various hydrocarbon radicals, such as acyclic, cyclic or heterocyclic, as well as simple aliphatic and aromatic compounds. In our copending application, Serial No. 99,160, we have described and claimed such thioethers and methods of preparing and isolating them.

The thioethers obtained by the methods of that application may advantageously be employed in the present invention. However, similar thioethers prepared by other methods may be here employed.

As stated ante, thioethers containing alkyl groups, such as the various amyl groups, are particularly effective for the present purposes. All the amylgroups give good materials for the present purposes. of these, the normal-amyl thioether of alpha anthraquinone is typical; the amyl compound has the following formula:

Commercial amyl preparations often contain all of the possible isomers and may be used in making mixed thioethers desirable for the present purposes. There are some specific advantages both in n-amyl and iso-amyl compositions. The same is true of the thioethers derived from the butyls and propyls; each has specific advantages in certain relations.

Other alkyl thioethers which are advantageous for the present purposes are:

Alpha-anthraquinone-ethy1-thioether Alpha-anthraquinone-butyl-thioether Alpha-anthraquinone-propyl-thioether These specific thioethers, especially advantageous for improving petroleum oils and mineral oil lubricants, as a sub-class may be represented by the following formula:

wherein n is 0 to 3. However, in the broad practice of this invention, other thioethers of alphaanthraquinone may be employed as stated ante.

These thioethers are quite stable even at the elevated operating temperatures usually encountered in the lubrication of alloy bearings." Also, they are substantially neutral in reaction. The properties of some of the alkyl thioethers,

ordinarily employed in the present invention, are as follows:

The above compounds are insoluble in water, slightly soluble in ethyl alcohol, and soluble in benzene. When crystallized as pure compositions from benzene they yield golden-yellow to red crystals. When dissolved in mineral oil, the oil is markedly colored. The color that is imparted to the improved oil gives it a pleasing appearance, for instance, the amyl thioether imparts a pleasing brilliant golden-yellow color to the oil.

The amyl thioether being liquid, has excellent blending qualities and is readily soluble in mineral oils at the usual blending temperatures of from to 280 F. By employing different thioethers of alpha-anthraquinone containing as the other group, any radical from either the aliphatic or aromatic series of hydrocarbons, we can obtain products of various properties, this being advantageous for particular embodiments of the present invention. These various products may be produced by selecting the proper mercaptan as the starting material.

Generally, the thioethers here employed are readily miscible and compatible with petroleum oils in the percentages necessary for the present purposes. They may be incorporated with the mineral oil or lubricating base in any suitable manner. They may be dissolved in the oil by simply mixing the thioether with the oil and slightly warming with agitation to obtain uniform lubricants. Warming to temperatures between 100 F. and 180 F. is usually sufflcient; the thioethers being readily soluble. With the heavier and more viscous lubricating oils this warming is advantageous since the heating low; ers the viscosity of the oil facilitating the blending. In some cases, the thioethers may be dissolved in suitable volatile solvents and the solution added to the oil, the solvent being subsequently distilled ofi. This solvent method is particularly effective with the solid thioethers. Also, the thioethers may be first dissolved in a suitable lubricating oil to form a master batch which is subsequently blended with more lubricating oil to give a range of lubricating compositions as desired. Likewise the compounded lubricant may be converted into thickened compositions or greases in any of the usual ways. Sometimes the thioether may be directly added to metal soap greases or other compounded lubricants in which a petroleum oil is the lubricating base.

In practicing the present invention any suitable lubricating oil base may be employed, either heavy or light oil. Ordinarily it is best to select a good grade of lubricating oil which has suitable initial properties for. the particular lubrication requirement. Then the addition of the thioether produces the additional desired characteristics of restraining their destructiveness toward the newer alloy bearing metals, etc. That is, petroleum oils and lubricants of the usual grades may be employed in practicing this invention. The oils falling within the well known S. A. E. classification are among those which can advantageously be improved by our invention. Likewise, special lubricants such as obtained by blending certain non-petroleum oil with mineral oil may be improved by the addition of these thioethers.

The corrosion and pitting of bearing metals by particular oils under drastic service conditions may be readily observed by visual inspection, but a special laboratory test is necessary to readily and quickly determine the destructive action of oil deterioration products on a standard, comparable and reproducible basis and to readily evaluate commercial lubricants for such alloy bearings. We have devised a satisfactory accelerated test procedure which is as follows:

An alloy bearing shell of certain commonly used standard dimensions is submerged in 300 cc. of the oil or oil composition in a 400 cc. pyrex beaker and heated in a thermostatically controlled oil bath to 1'75 C. (347 F.) and air, at the rate of 2000 cc. per hour, is bubbled through the oil in contact with the bearing shell. At the end of 48 and 96 hours, the loss of weight and the condition of the bearing shell are determined. This test will hereinafter be referred to as our standard laboratory test.

In determining the loss in weight the bearing shell is washed free of oil and dried before weighing.

When determining the effectiveness of various improvement agents the usual procedure is to run a blank test simultaneously with the oil composition being tested, employing for that purpose a sample of the untreated oil.

In such tests it is advantageous to employ commercial bearing shells. These shells comprise a suitable metal backing faced with the alloy bearing metal. is bubbled against the alloy bearing face. In this way, the actual bearing face is subjected to In the above test, the airsevere deteriorative conditions. By comparison of the results of such tests with actual service tests, we have found them to be in substantial agreement as to the suitability of particular lubricants.

In testing our lubricants, we have employed, among others, bearings of the following approximate composition:

1. Cadmium-silver alloy CS 7610 Per cent Cadmium 98 Silver 1 Copper 1 2. Dead-copper alloy 9020 CA Per cent Lead 45 Copper 53 Nickel 2 Such alloys are used in the tests of illustrative improved lubricants given post. In such tests the loss in weight, while not extremely high when expressed as per cent loss, is nevertheless very significant, as the bearing shells used have an alloy facing of only 0.008 inch to 0.012 inch thickness on a highly resistant backing and the observed losses in the reported tests often represent a loss of the order of per cent of the alloy facing. I

The specific examples and tests given post are illustrative of detail embodiments of the present invention.

Example 1.-Into a suitable vessel there were introduced 1000 gallons (approximately 7200 pounds) ofPennsylvania motor oil 5. A. E. 10 grade and the oil was warmed to 160 F. Then 7.2 pounds of the amyl-thioether of alpha-anthraquinone (0.10 per cent by weight on the oil) was gradually added and the mixture agitated until a uniform blend was obtained; about 1 hour being required. In agitating the mixture, ordinary mechanical agitators may be employed or a current of air may be passed through the warm mixture to produce uniform blending.

The properties of the original and improved motor oil are as follows:

Table A Original Improved oil lubricant Gravity: A. P. I 33.1 33, 1 Viscosity: S.U.V:

100 F 180. 2 180. 2 46. 2 46. 2 420 420 490 490 0 0 l. 25 1. 75 .02 ,02 Satisfactory Satisfactory From the above table it is clear that the addition of the amyl thioether of alpha-anthraquinone does not substantially change the ordinary properties of the oil.

When tested by the standard laboratory test given ante, using a commercial bearing shell faced with a cadmium silver alloy containing approximately 98 parts of cadmium to 1 part of silver and 1 part of copper, the following results were obtained in 48 hour test runs, on the original oil and on the improved oil.

From the above results, the beneficial eflect of the amyl thioether as an improvement agent for the oil is quite apparent. This improved lubricant when tested in an automobile engine equipped with like bearings was highly satisfactory and no destructive effect on the bearing was observed after a severe test run. Thus the standard laboratory test and actual service test gave similar results.

Example 2.In Example 1, by substituting the butyl thioether of alpha-anthraquinone, another advantageous improved lubricant is obtained. It has the following properties:

i This improved oil when subjected to ,the standard laboratory test gave the following results:

Table D Bearing shell weight:' Original oil Improved lubricant Grams Grams Before test 27. 7925 27. 2636 After test 27. 3781 27. 2650 Total change 0. 4144 +0. 0014 Comment Significant 10s..-. Insignificant gain. Bearing appearance (alter Badly etched and No change.

test). pitted.

Example 3.-By employing a Pennsylvania motor oil of S. A. E. 40 grade, as in Example 1, in lieu of the S. A. E. 10 grade oil and by adding 0.5% by weight of alpha-anthraquinone thioether still another advantageous lubricant is obtained.

This improved motor oil, likethe improved motor oils obtained in Examples 1 and 2, has increased film strength in addition to being noncorrosive to alloy bearings. That is, we impart. extreme pressure characteristics to the lubricating oil base by incorporating these thioethers therein. The increased film strength of our improved lubricant may be readily determined on the Almen lubrication testing machine using the standard procedure for such tests. For instance, the original oil withstood only 4000 pounds per square inch maximum load, while the improved lubricant withstood a maximum load of 8000 pounds per square inch. Other thioethers may the percentage of thioethers employed may be varied as indicated, according to the particular thioethers employed and according to the particular properties desired in the final lubricant. Likewise, the lubricating base itself may be selected according to the type oi final lubricant to be produced. For instance, any 01' the usual greases or the usual blends of inineral andnonmineral oils may be employed as a lubricating base in making lubricants of our improved type. The addition of the thioethers to these lubricating bases produces a like improvement in film strength and reduces their destructiveness toward the newer alloy bearing metals. When incorporating the thioethers in a grease composition or like thickened lubricant, mechanical agitators rather than a current oi air are employed to obtain uniform mixing and blending. That is, the thioether and grease may be compounded in the usual mixers such as blade mixers, equipped with heating jackets. However, in making such greases the thioether may advantageously be first incorporated with the oil base according to the procedure of Example 1 and then the metal soap or the thickening agents added to the improved oil,'in the ordinary way to produce the desired grease compositions. In other words, the improved mineral oils of the present invention may be used in lieu of the ordinary oils in making special lubricating compositions such as greases, etc.

The ethyl thioether of alpha-anthraquinone and other thioethers may be employed in lieu oi the amyl and butyl thioethers given in the examples. In fact, the thioethers derived from aryl mercaptans are useful in many embodiments of the present invention, such as the aryl thioethers obtained by reacting alpha-anthraquinone sodium sul'ionate with aryl mercaptans. With proper blending, good lubricants may be produced with all these thioethers compounded with various petroleum oils or mineral oil lubricants. 4

As stated ante, the incorporation of these thioethers with the lubricating base produces several improvements in the final lubricant without deleteriously affecting the desirable properties. While the exact reasons for the improvements obtained are not fully known, we are satisfied with observing and utilizing the actual improvements obtained by adding and incorporating these thioethers with commercial lubricants.

What we claim is:

1. An improved lubricant comprising principally a mineral lubricating oil, which oil has been improved by the addition thereto of a small amount of an organic thioether of alpha-anthraquinone.

2. The improved lubricant of claim 1 wherein said organic thioether is an alkyl thioether of alpha-anthraquinone.

3. The improved lubricant of claim 1 wherein said organic thioether is an aryl thioether oi! alpha-anthraquinone. v

4. The improved lubricant of claim 1 wherein said mineral lubricating oil contains between 0.02 to 1.0 per cent of saidthioether.

5. As an article of manufacture an improved lubricant comprising a. major portion of a mineral lubricating oil and minor proportion of an alkyl thioether of alpha-anthraquinone.

6. The improved lubricant of claim 5 wherein said thioether is the amyl thioether of alphaanthraquinone.

'7. As a new article of manufacture an improved lubricant comprising mineral lubricating oil containing dissolved therein between 0.02 to 1.0 per cent of the amyl thioether of alpha-anthraquinone.

8. The improved lubricant of claim 1 wherein said organic thioether is the ethyl thioether of alpha anthraquinone.

9. The improved lubricant of claim 1 wherein said organic thioether is the butyl ether of alpha anthraquinone.

10. The improved lubricant of claim 1 wherein said organic thioether is the amyl thioether of alpha anthraquinonek TROY LEE CANTREIL. JAMES OTHO TURNER. 

